Designing of amino silica covalently functionalized carboxylic multi-wall carbon nanotubes-based polyethersulfone membranes for enhancing oily wastewater treatment

Abstract

The accumulation of oily wastewater is a critical issue that can cause environmental pollution. Membrane technology can play a vital role in the treatment of oily wastewater due to its productivity and economical cost. In this work, the amino silica covalently functionalized carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) nanohybrid was synthesized and blended with polyethersulfone (PES) membranes for oil/water separation to enhance the antifouling property. Membranes were fabricated with various loadings of SiO2-f-MWCNTs nanohybrid (0–2 wt%) using phase inversion technique. The incorporation of nanohybrid resulted in the enhancement of wettability and pore size distribution of nanocomposite membranes. The morphological structure, surface and chemical features of the synthesized membranes were examined using scanning electron microscopy, Fourier transform infrared spectroscopy, water contact angle and X-ray diffraction analyses. Furthermore, the impact of nanohybrid blending with PES membrane on water permeability and oil rejection was investigated. The water permeability enhanced from 188 ± 8 L/m2.h.bar, for the pristine PES membrane, to 293 ± 9 L/m2.h.bar for nanocomposite membrane blended with 2 % SiO2-f-MWCNTs nanohybrid. Similarly, the oil rejection was improved up to 97 ± 0.1 % using the same nanohybrid loading. The results revealed that using 2 % nanohybrid loading has increased the humic acid (HA) flux by 16 %, while the irreversible HA fouling was significantly reduced to 0.9 % compared to 9.9 % for the pristine PES.